The present invention relates to a gas insulation switchgear, and more particularly, to a compressed gas insulation switchgear for a commercial extra-high voltage power receiving and transforming facility.
Conventional compressed gas insulation switchgears for commercial extra-high voltage power receiving and transforming facilities are classified into those of a single metering system and those of a dual metering system. As described, for example, in Japanese Patent Laid-open (Kokai) No. 1-303002, the compressed gas insulation switchgear of the former metering system receives power through two lines, and has one potential current transformer and two transformers connected to the potential current transformer. Although this compressed gas insulation switchgear receives power through the two lines to enhance reliability in power supply, power supply to the customer must be stopped when the potential current transformer is stopped for inspection or replacement. As described, for example, in Japanese Patent hid-open (Kokai) No. 1-248911, the compressed gas insulation switchgear of the latter metering system is provided with two potential current transformers, and one of the two potential current transformers is used for measuring consumed electric energy while the other potential current transformer is stopped for inspection to avoid stopping power supply.
FIG. 15 is a skeleton diagram of the compressed gas insulation switchgear of the latter metering system.
The respective transformer ends of two power receiving units LU1 and LU2 are interconnected by a connecting conductor CU1, the respective receiving ends of transformer side units TU1 and TU2 are interconnected by a connecting conductor CU2, and two potential current transformer units PU1 and PU2 are in parallel to the connecting conductors CU1 and CU2. When inspecting a potential current transformer 13 or replacing the same with another one, disconnectors connected respectively to the opposite ends of the potential current transformer unit PU1 are operated to disconnect the potential current transformer unit PU1 from the circuit, and the other potential current transformer unit PU2 is connected to the circuit, so that power supply to the customer is not interrupted.
Although the compressed gas insulation switchgear provided with the two potential current transformers is able to avoid the stoppage of power supply to the customer as mentioned above, the compressed gas insulation switchgear is very large as compared with a compressed gas insulation switchgear provided with one potential current transformer. FIG. 16 is a plan view of the compressed gas switchgear shown in FIG. 15 in a skeleton diagram.
The two power receiving units LU1 and LU2 are disposed opposite to each other, the respective transformer side ends of the power receiving units LU1 and LU2 are interconnected by the connecting unit CU1, the transformer side units TU1 and TU2 on the side of transformers TR1 and TR2 are disposed opposite to each other, the respective power receiving ends are interconnected by the connecting units CU2, and the potential current transformer units PU1 and PU2 respectively provided with the potential current transformers 13 are connected in parallel to the connecting units CU1 and CU2. Since the components of the compressed gas insulation switchgear are arranged in a closed loop in a plane, the compression gas insulation switchgear needs a very large area for installation.
In FIG. 17 and in a plan view in FIG. 18, a compressed gas insulation switchgear is show, similar to that disclosed in Japanese Patent Application No. 4-256618 (incorporated herein by reference), which was laid open after the priority date of the present application, and therefore is not prior art. The switch gear shown in FIG. 17 and 18 comprises two potential current transformer units PU1 and PU2, transformer side units TU1 and TU2 disposed respectively on the opposite ends of the two potential current transformer units PU1 and PU2, and power receiving units LU1 and LU2 disposed respectively on the respective outer sides of the transformer side units TU1 and TU2. This compressed gas insulation switchgear needs a comparatively small area for installation. Also, this switch gear is provided with two potential current transformer units PU1 and PU2 and provides enhanced power supply reliability while reducing the area required for installation. However, when installing another bank to deal with increase in power demand, the connection of an additional transformer side unit and the secondary side of an additional potential current transformer is obstructed by the power receiving unit LU1 when the components are arranged as shown in FIG. 18. Consequently, when the additional transformer unit is installed on the outer side of the power receiving unit in a line, a connecting bus cannot be extended linearly, much time and labor is required to install the connecting bus, and the size of the compressed gas insulation switchgear increases.
If trouble occurs in the connecting unit CU2 interconnecting the secondary sides of the potential current transformer units PU1 and PU2 of the compressed gas insulation switchgears shown in FIGS. 15 and 17 in skeleton diagrams, the transformer TR2 is stopped when the potential current transformer unit PU1 is a service potential current transformer unit and the potential current transformer unit PU2 is a standby potential current transformer unit or the transformer TR1 is stopped when the potential current transformer unit PU1 is a standby potential current transformer unit and the potential current transformer unit PU2 is a service potential current transformer unit and, consequently, the compressed gas insulation switchgear is unable to continue normal operation.
Two other documents also show in-row cubicles, but poor transformer tap access. They are: (1) Japanese application number 5-56520, laid open Mar. 5, 1993, and the subject of a U.S. application number Ser. No. 08/079,798, having an inventor in common with the present application and being commonly owned, priority to which is claimed herein, and (2) Japanese application number 5-21965, laid open Apr. 27, 1993.
A first object of the present invention is to provide a compressed gas insulation switchgear that can be installed in a comparatively small area.
A second object of the present invention is to provide a compressed gas insulation switchgear capable of readily dealing with installing an additional bank.